DESCRIPTION OF SHARED RESOURCE The Experimental Irradiator Core, which has been in existence since 1986, maintains and operates sources of ionizing radiation for use by Sidney Kimmel Comprehensive Cancer Center (SKCCC) members in their experimental studies. Services performed by the resource staff include training in the operation of the sources, advice to users on the design of experiments using radiation, scheduling use of the sources, operating the sources when necessary, dosimetry for new experimental setups, and maintenance and repair of the resources. When not in use by members, these facilities are also available to non-members on an increased-fee basis. The primary resources of the facility are five Cs-137 irradiators and one image guided orthovoltage x-ray tube irradiator (SARRP). Two Nordion Gammacell 40 in-adiators are primarily used for whole body irradiation of rodents or irradiation of attached cultured cells at a constant dose rate. The Shepherd Mark I irradiator is used primarily to deliver radiation to animal tumors or other partial-body irradiations at dose rates comparable to those used in external beam radiotherapy. However, this irradiator can deliver radiation at a broad range of dose rates for a variety of purposes, such as irradiation of cell suspensions or irradiation to high doses to sterilize implant material. The Gammacell 1000 irradiator is used to irradiate suspension cultures at a constant dose rate. The low-dose-rate irradiator, built in-house with a Shepherd 81 source, is used primarily to irradiate cell cultures at dose rates comparable to those used in tumor therapy with radioactive implants, but can deliver radiation at any rate below two Gy/hr and has also been used in studies of carcinogenesis from prolonged exposure to low-dose-rate radiation. An in-house built image-guided small animal radiation research platform (SARRP) is now available to the Core facility and is located in the David Koch Cancer Research Building (CRBll). The SARRP is designed to produce the same degree of dose delivery precision in animal models as is currently achievable in human patients. Lay The Experimental Irradiator Core allows researchers to deliver specific doses of radiation to a wide range of biological materials and live animals. Depending on a researcher's experimental design, these instruments can irradiate blood products, whole bodies of animals or direct a radiation beam to a small tumor on a mouse. SKCCC Managed Shared Resource Current Grant Year Reporting Period: January 1, 2010 to December 31, 2010.